Air conditioner

ABSTRACT

The present invention is capable of eliminating the line unit in an air conditioner that includes a plurality of heat source units, and hold increases in onsite line construction to a minimum while making it possible to adjust the amount of refrigerant in the air conditioner. The air conditioner includes a plurality of heat source units, a refrigerant liquid junction line and a refrigerant gas junction line, user units, and a refrigerant supply circuit. The refrigerant supply circuit is used in situations in which some of the plurality of heat source units stop operating in response to the operational burden of the user units, and is formed from refrigerant removal lines that remove refrigerant that accumulates inside stopped heat source units to the exterior thereof, and an oil equalization line and oil removal lines that connect the refrigerant removal lines of each stopped heat source unit and the intake sides of the compression mechanisms of the operating heat source units.

TECHNICAL FIELD

The present invention relates to an air conditioner, and moreparticularly to an air conditioner having a plurality of heat sourceunits.

BACKGROUND ART

In some conventional air conditioners having a plurality of heat sourceunits, heat source side branch liquid lines and heat source side branchgas lines of the plurality of heat source units are connected to aseparately provided line unit, and the heat source side branch liquidlines and the heat source side branch gas lines are merged togetherinside the line unit as a refrigerant liquid junction line and arefrigerant gas junction line and connected to user units.

This line unit not only functions to integrate the aforementioned heatsource side branch liquid lines and the heat source side branch gaslines into a refrigerant liquid junction line and a refrigerant gasjunction line, but when some of the plurality of heat source units stopoperating in response to the operational burden of the user units, theline unit also functions to accumulate refrigerant inside the stoppedheat source units to prevent a shortage in the refrigerant that flowsbetween the user units and the operating heat source units.

With this type of air conditioner, the heat source side branch liquidlines and the heat source side branch gas lines of each heat source unitcan be merged together into a refrigerant liquid junction line and arefrigerant gas junction line by simply connecting the heat source sidebranch liquid lines and the heat source side branch gas lines to theline unit, and thus the ability to construct the air conditioner at thelocation in which it is to be installed can be improved (see, forexample, Japanese Published Unexamined Patent Application No.H06-249527).

However, from a manufacturing viewpoint, the line unit of theaforementioned conventional air conditioner must be manufactured andstored as inventory, and thus causes costs to increase. Thus, there is aneed to eliminate the line unit when seen from the perspective ofmanufacturing these units.

SUMMARY OF THE INVENTION

An object of the present invention is to eliminate the line unit in anair conditioner that includes a plurality of heat source units, and holdincreases in onsite line construction to a minimum while making itpossible to adjust the amount of refrigerant in the air conditioner.

According to a first aspect of the present invention, an air conditionerincludes a plurality of heat source units, a refrigerant liquid junctionline and a refrigerant gas junction line, user units, and a refrigerantsupply circuit. The heat source units each include a compressionmechanism and a heat source side heat exchanger. The refrigerant liquidjunction line and the refrigerant gas junction line parallel connecteach heat source unit. The user units each include a user side heatexchanger, and are connected to the refrigerant liquid junction line andthe refrigerant gas junction line. The refrigerant supply circuit isused in situations in which some of the heat source units have stoppedoperating in response to the operational burden of the user units, andincludes a refrigerant removal line provided in each heat source unitthat serves to remove to the exterior of the stopped heat source unitsthe refrigerant that accumulates in the interior of the heat sourceunits, and a communication line that connects the refrigerant removallines and the intake side of the compression mechanisms of the operatingheat source units.

In this air conditioner, equipment control is performed in which, forexample, some of the plurality of the heat source units are stopped inresponse to the operational burden of the user units. Thus, duringcooling operations, refrigerant gas discharged from the compressionmechanisms in the operating heat source units is condensed by the heatsource side heat exchangers into refrigerant liquid and merged into therefrigerant liquid junction line, the refrigerant liquid is evaporatedinto refrigerant gas by the user side heat exchangers of the user units,and the refrigerant gas is drawn into the compression mechanisms of theoperating heat source units via the refrigerant gas junction line. Inaddition, during heating operations, refrigerant gas discharged from thecompression mechanisms is merged together in the refrigerant gasjunction line, the refrigerant gas is condensed by the user side heatexchangers of the user units into refrigerant liquid, the refrigerantliquid is sent to the operating heat source units via the refrigerantliquid junction line, the refrigerant liquid is evaporated intorefrigerant gas by the heat source side heat exchangers, and therefrigerant gas is drawn into the compression mechanisms of theoperating heat source units. On the other hand, the refrigerant supplycircuit is employed to supply refrigerant accumulated inside the stoppedheat source units to the intake sides of the compression mechanisms ofthe operating heat source units, so that there will be no shortage ofrefrigerant flowing between the user units and the operating heat sourceunits.

Here, the refrigerant supply circuit includes the refrigerant removallines that remove to the exterior of the heat source units refrigerantthat accumulates in the interior of the heat source units, and acommunication line that connects the refrigerant removal lines and theintake sides of the compression mechanisms of the operating heat sourceunits. In other words, a function that adjusts the quantity ofrefrigerant so that there are no shortages thereof is achieved in thisair conditioner by simply providing essential components that form therefrigerant supply circuit in the interior of the heat source units, andproviding a communication line between the heat source units. Thisallows the line unit provided in the prior art to be eliminated, andallows increases in onsite line construction to be held to a minimumwhile preventing refrigerant shortages.

According to a second aspect of the present invention, the airconditioner of the first aspect of the present invention is provided, inwhich the heat source side heat exchangers are connected to thedischarge sides of the compression mechanisms. Each heat source unitfurther includes a heat source side branch liquid line that is connectedto the liquid side of the heat source side heat exchanger and therefrigerant liquid junction line, a receiver that is provided on theheat source side branch liquid line, and a heat source side branch gasline that is connected to the intake side of the compression mechanismand the refrigerant gas junction line. Each refrigerant removal line isarranged such that it removes refrigerant from between the dischargeside of the compression mechanism and the gas side of the heat sourceside heat exchanger.

During cooling operations with this air conditioner, because arefrigerant removal line is provided between the discharge sides of eachcompression mechanism and the gas sides of each heat source side heatexchanger, the portion of the accumulated refrigerant inside eachstopped heat source unit that exists from the discharge side of thecompression mechanism to the heat source side branch liquid line(including the receiver) will be supplied to the operating heat sourceunits via the refrigerant removal line. At this point, the refrigerantliquid accumulated inside the receiver is evaporated by the heat sourceside heat exchanger, and then supplied to the operating heat sourceunits via the refrigerant removal line.

According to a third aspect of the present invention, the airconditioner of the second aspect is provided, in which each heat sourceside branch liquid line includes a refrigerant open/close mechanism thatcloses so that refrigerant will not flow from the refrigerant liquidjunction line to the interior of a stopped heat source unit whenrefrigerant accumulated inside the stopped heat source unit is to beremoved to the exterior thereof via the refrigerant removal line.

In this air conditioner, refrigerant accumulated in a stopped heatsource unit can be removed to the exterior of the heat source unit withgood efficiency by means of the refrigerant open/close mechanism,because the refrigerant open/close mechanism can be closed so thatrefrigerant will not flow from the refrigerant line junction line to theinterior of the stopped heat source unit.

According to a fourth aspect of the present invention, the airconditioner of the third aspect of the present invention is provided, inwhich the refrigerant open/close mechanism can make refrigerant liquidthat flows in the refrigerant liquid junction line flow into theinterior of a stopped heat source unit when the quantity of refrigerantthat flows between the user units and the operating heat source unitsreaches an excessive state.

In this air conditioner, when the quantity of refrigerant that flowsbetween the user units and the operating heat source units reaches anexcessive state, the quantity of refrigerant in the operating heatsource units can be reduced by operating the refrigerant open/closemechanism to make refrigerant that flows in the refrigerant liquidjunction line flow into a stopped heat source unit and accumulate in thereceiver thereof. This allows the quantity of refrigerant in the airconditioner to be adjusted.

According to a fifth aspect of the present invention, the airconditioner of the first aspect of the present invention is provided, inwhich the heat source side heat exchangers are connected to the intakesides of the compressor mechanisms. Each heat source unit furtherincludes a heat source side branch liquid line that is connected to theliquid side of the heat source side heat exchanger and the refrigerantliquid junction line, a heat source side branch gas line that isconnected to the discharge side of the compression mechanism and therefrigerant gas junction line, and a receiver that is provided on theheat source side branch liquid line. The refrigerant removal line isarranged such that it removes refrigerant from between the intake sideof the compression mechanism and the gas side of the heat source sideheat exchanger.

During heating operations with this air conditioner, because therefrigerant removal line is provided between the intake side of thecompression mechanism and the gas side of the heat source side heatexchanger, the portion of the accumulated refrigerant inside a stoppedheat source unit that exists from the intake side of the compressionmechanism to the heat source side branch liquid line (including thereceiver) will be supplied to the operating heat source units via therefrigerant removal line. At this point, the refrigerant liquidaccumulated inside the receiver is evaporated by the heat source sideheat exchanger, and then supplied to the operating heat source units viathe refrigerant removal line.

According to a sixth aspect of the present invention, the airconditioner of the fifth aspect of the present invention is provided, inwhich each heat source side branch liquid line includes a refrigerantopen/close mechanism that closes so that refrigerant will not flow fromthe refrigerant liquid junction line to the interior of a stopped heatsource unit when refrigerant accumulated inside the stopped heat sourceunits is to be removed to the exterior of the heat source units via therefrigerant removal line.

In this air conditioner, because the refrigerant open/close mechanismcan be closed so that refrigerant will not flow from the refrigerantliquid junction line to the interior of a stopped heat source unit,refrigerant accumulated in the stopped heat source unit can be removedto the exterior of the heat source unit with good efficiency by means ofthe refrigerant open/close mechanism.

According to a seventh aspect of the present invention, the airconditioner of the sixth aspect of the present invention is provided, inwhich a stopped heat source unit further includes a receiverpressurization circuit that makes some of the refrigerant that flows inthe refrigerant gas junction line flow into the receiver via the heatsource side branch gas line.

In this air conditioner, the refrigerant liquid accumulated in thereceiver can be discharged to the heat source side branch liquid linewith the refrigerant open/close mechanism in the closed state becausethe receiver can be pressurized by means of the receiver pressurizationcircuit.

According to an eighth aspect of the present invention, the airconditioner of the sixth or seventh aspects of the present invention isprovided, in which the refrigerant open/close mechanism can makerefrigerant liquid that flows in the refrigerant liquid junction line toflow into the interior of a stopped heat source unit when the quantityof refrigerant that flows between the user units and the operating heatsource units reaches an excessive state.

In this air conditioner, when the quantity of refrigerant that flowsbetween the user units and the operating heat source units reaches anexcessive state, the quantity of refrigerant that flows between the userunits and the operating heat source units can be reduced by operating arefrigerant open/close mechanism to make refrigerant that flows in therefrigerant liquid junction line flow into a stopped heat source unitand accumulate in the receiver thereof. This allows the quantity ofrefrigerant in the air conditioner to be adjusted.

According to a ninth aspect of the present invention, the airconditioner of any one of the first to eighth aspects of the presentinvention is provided, in which the communication line is an oilequalization line that equally distributes oil between the compressionmechanisms of each heat source unit.

With this air conditioner, onsite line construction can be furtherreduced because the junction line also serves as an oil equalizationline.

According to a tenth aspect of the present invention, an air conditionerincludes a plurality of heat source units, a refrigerant liquid junctionline and a refrigerant gas junction line, user units, and receiverdepressurization circuits. Each heat source unit includes a compressionmechanism, a heat source side heat exchanger that is connected to theintake side of the compression mechanism, and a receiver that isconnected to the liquid side of the heat source side heat exchanger. Therefrigerant liquid junction line and the refrigerant gas junction lineparallel connect each heat source unit. Each user unit includes a userside heat exchanger, and is connected to the refrigerant liquid junctionline and the refrigerant gas junction line. The receiverdepressurization circuits make refrigerant flow out from the receiversof the heat source units that have a shortage of refrigerant to theintake sides of the compression mechanisms.

In this air conditioner, refrigerant gas discharged from the compressormechanisms is merged together in the refrigerant gas junction line, therefrigerant gas is condensed by the user side heat exchangers of theuser units into refrigerant liquid, the refrigerant liquid is sent tothe operating heat source units via the refrigerant liquid junctionline, the refrigerant liquid is evaporated into refrigerant gas by theheat source side heat exchangers, and the refrigerant gas is drawn intothe compressor mechanisms of the operating heat source units.

Here, refrigerant liquid will be unequally distributed to each heatsource unit in situations in which all of the heat source units areoperating and the refrigerant that flows in the refrigerant liquidjunction line is in the gas-liquid phase. In this type of situation, thequantity of refrigerant liquid to be supplied to certain heat sourceunits will be reduced, and a refrigerant shortage will be created.

However, in this air conditioner, because heat source unit includes thereceiver depressurization circuits, the quantity of refrigerant thatwill flow from the refrigerant liquid junction line into the heat sourceunits in which there is a refrigerant shortage can be increased bymaking refrigerant flow from the receivers of the heat source units inwhich there is a shortage of refrigerant to the intake sides of thecompressor mechanisms thereof. This allows refrigerant shortages to beeliminated, and allows the quantity of refrigerant to be sent from therefrigerant liquid junction line to each heat source unit to bemaintained at an appropriate flow rate balance. This allows the lineunit provided in the prior art to be eliminated, and allows increases inonsite line construction to be held to a minimum while preventingrefrigerant shortages.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of an airconditioner according to an embodiment of the present invention.

FIG. 2 is an outline of a refrigerant circuit of a heat source unit ofan air conditioner according to the present invention.

FIG. 3 is an outline of the refrigerant circuits of heat source unitswhen all the heat source units are conducting cooling operations.

FIG. 4 is an outline of the refrigerant circuits of heat source unitswhen only a portion of a plurality of heat source units are conductingcooling operations, and the other heat source units are stopped.

FIG. 5 is an outline of the refrigerant circuits of heat source unitswhen only a portion of a plurality of heat source units are conductingcooling operations, and the other heat source units are stopped.

FIG. 6 is an outline of the refrigerant circuits of heat source unitswhen all the heat source units are conducting heating operations.

FIG. 7 is an outline of the refrigerant circuits of heat source unitswhen only a portion of a plurality of heat source units are conductingheating operations, and the other heat source units are stopped.

FIG. 8 is an outline of the refrigerant circuits of heat source unitswhen only a portion of a plurality of heat source units are conductingheating operations, and the other heat source units are stopped.

FIG. 9 is a block diagram showing the configuration of a conventionalair conditioner.

PREFERRED EMBODIMENT OF THE INVENTION

An air conditioner according an embodiment of the present invention willbe described below with reference to the figures.

(1) Overall Configuration of the Air Conditioner

FIG. 1 is a block diagram showing the configuration of an airconditioner according to an embodiment of the present invention. An airconditioner 1 includes first, second, and third heat source units 102a–102 c (three units in the present embodiment), a refrigerant liquidjunction line 4 and a refrigerant gas junction line 5 that serve toserially connect the heat source units 102 a–102 c, and a plurality ofuser units 3 a, 3 b (2 units in this embodiment) that are parallelconnected to the refrigerant liquid junction line 4 and the refrigerantgas junction line 5. More specifically, heat source side branch liquidlines 11 a–11 c of the heat source units 102 a–102 c are respectivelyconnected to the refrigerant liquid junction line 4, and the heat sourceside branch gas lines 12 a–12 c of the heat source units 102 a–102 c arerespectively connected to the refrigerant gas junction line 5.

In addition, the heat source units 102 a–102 c include compressionmechanisms 13 a–13 c that include one or more compressors. An oilequalization line 6 is provided between these compression mechanisms 13a–13 c, and allows oil to be exchanged between the heat source units 102a–102 c.

This air conditioner can increase or decrease the number of heat sourceunits 102 a–102 c in operation in response to the operational burden ofthe user units 3 a, 3 b.

(2) Configuration of the User Units

Next, the user units 3 a, 3 b will be described. Note that because theconfigurations of the user unit 3 a and the user unit 3 b are the same,only details regarding the user unit 3 a will be disclosed, and adescription of the user unit 3 b will be omitted.

The user unit 3 a primarily includes a user side expansion valve 61 a, auser side heat exchanger 62 a, and a line that that connects these. Inthe present embodiment, the user side expansion valve 61 a is anelectric expansion valve that is connected to the liquid side of theuser side heat exchanger 62 a, and serves to adjust the refrigerant flowrate and the like. In the present embodiment, the user side heatexchanger 62 a is a cross fin tube type of heat exchanger, and serves toexchange heat with indoor air. In the present embodiment, the user unit3 a takes in indoor air into the interior thereof, includes an indoorfan for blowing (not shown in the figures), and is capable of exchangingheat between the indoor air and the refrigerant that flows in the userside heat exchanger 62 a.

In addition, various sensors are provided in the user unit 3 a. A liquidside temperature sensor 63 a that detects the refrigerant liquidtemperature is arranged on the liquid side of the user side heatexchanger 62 a, and a gas side temperature sensor 64 a that detects therefrigerant gas temperature is arranged on the gas side of the user sideheat exchanger 62 a. Furthermore, a room temperature sensor 65 a thatdetects the temperature of indoor air is provided in the user unit 3 a.

(3) Configuration of the Heat Source Units

Next, the first, second and third heat source units 102 a–102 c will bedescribed with reference to FIG. 2. Here, FIG. 2 shows an outline of arefrigerant circuit of the first heat source unit 102 a. Note that inthe description below, only the details of the first heat source unit102 a will be disclosed, and a description of the second and third heatsource units 102 b, 102 c will be omitted because the first heat sourceunit 102 a has the same configuration as the second and third heatsource units 102 b, 102 c.

The heat source unit 102 a primarily includes a compression mechanism 13a, a four way switching valve 14 a, a heat source side heat exchanger 15a, a bridge circuit 16 a, a receiver 17 a, a liquid side gate valve 18a, a gas side gate valve 19 a, an oil removal line 20 a, a refrigerantremoval line 21 a, a receiver pressurization circuit 22 a, a receiverdepressurization circuit 23 a, and a line that connects these.

The compression mechanism 13 a primarily includes a compressor 31 a, anoil separator (not shown in the figures), and a check valve 32 a that isprovided on the discharge side of the compressor 31 a. In the presentembodiment, the compressor 31 a is an electric motor driven scroll typecompressor, and serves to compress refrigerant gas that has been drawntherein.

When switching between cooling operations and heating operations, thefour way switching valve 14 a serves to switch the direction of therefrigerant flow. During cooling operations, the four way switchingvalve 14 a connects the discharge side of the compression mechanism 13 aand the gas side of the heat source side heat exchanger 15 a, andconnects the intake side of the compression mechanism 13 a and the heatsource side branch gas line 12 a (refer to the solid line of the fourway switching valve 14 a in FIG. 2). During heating operations, the fourway switching valve 14 a connects the discharge side of the compressionmechanism 13 a and the heat source side branch liquid line 11 a, andconnects the intake side of the compression mechanism 13 a and the gasside of the heat source side heat exchanger 15 a (refer to the brokenline of the four way switching valve 14 a in FIG. 2).

In the present embodiment, the heat source side heat exchanger 15 a is across fin tube type of heat exchanger, and serves to exchange heatbetween air and refrigerant that acts as a heat source. In the presentembodiment, the heat source unit 102 a takes in outdoor air into theinterior thereof, includes an outdoor fan for blowing (not shown in thefigures), and is capable of exchanging heat between the outdoor air andthe refrigerant that flows in the heat source side heat exchanger 15 a.

The receiver 17 a is a vessel that serves to temporarily accumulaterefrigerant that flows between the heat source side heat exchanger 15 aand the user side heat exchangers 62 a, 62 b of the user units 3 a, 3 b.The receiver 17 a includes an intake port on the upper portion of thevessel, and a discharge port on the lower portion of the vessel. Theintake port and the discharge port of the receiver 17 a are respectivelyconnected to the heat source side branch liquid line 11 a via the bridgecircuit 16 a.

The bridge circuit 16 a includes three check valves 33 a–35 a that areconnected to the heat source side branch liquid line 11 a, a heat sourceside expansion valve 36 a, and a first open/close mechanism 37 a. Thebridge circuit 16 a functions to make refrigerant flow from the intakeport side of the receiver 17 a into the receiver 17 a, as well as returnrefrigerant liquid from the discharge port of the receiver 17 a to theheat source side branch liquid line 11 a, either when refrigerant thatflows in the refrigerant circuit between the heat source side heatexchanger 15 a and the user side heat exchangers 62 a, 62 b flows fromthe heat source side heat exchanger 15 a to the receiver 17 a, or whenrefrigerant that flows in the refrigerant circuit between the heatsource side heat exchanger 15 a and the user side heat exchangers 62 a,62 b flows from the user side heat exchangers 62 a, 62 b to the receiver17 a. More specifically, the check valve 33 a is connected such thatrefrigerant that flows in the direction from the user side heatexchangers 62 a, 62 b to the heat source side heat exchanger 15 a isguided to the intake port of the receiver 17 a. The check valve 34 a isconnected such that refrigerant that flows in the direction from theheat source side heat exchangers 15 a to the user side heat exchangers62 a, 62 b is guided to the intake port of the receiver 17 a. The checkvalve 35 a is connected such that refrigerant can flow from thedischarge port of the receiver 17 a to the user side heat exchangers 62a, 62 b. The heat source side expansion valve 36 a is connected suchthat refrigerant can flow from the discharge port of the receiver 17 ato the heat source side heat exchanger 15 a. In addition, in the presentembodiment, the heat source side expansion valve 36 a is an electricexpansion valve that serves to adjust the refrigerant flow rate betweenthe heat source side heat exchanger 15 a and the user side heatexchangers 62 a, 62 b. The first open/close mechanism 37 a is arrangedso that it can allow or prevent the refrigerant to flow from the liquidside gate valve 18 a toward the receiver 17 a. In the presentembodiment, the first open/close mechanism 37 a is a solenoid valve thatis arranged on the liquid side gate valve 18 a side of the check valve33 a. In this way, the refrigerant that flows from the heat source sidebranch liquid line 11 a into the receiver 17 a will always flow thereinfrom the intake port of the receiver 17 a, and the refrigerant from thedischarge port of the receiver 17 a will always be returned to the heatsource side branch liquid line 11 a.

The oil removal line 20 a is an oil line that serves to exchange oilbetween the compression mechanism 13 a and the second heat source unit102 b and the third heat source unit 102 c, and includes an oildischarge line 38 a that discharges oil to the exterior of thecompressor 31 a when the quantity of oil in an oil accumulation portionof the compressor 31 a exceeds a predetermined quantity, and an oilreturn line 39 a that is branched from the oil discharge line 38 a andwhich can return oil to the intake side of the compression mechanism 13a. The oil discharge line 38 a is formed from a check valve 40 a, acapillary 41 a, an oil gate valve 42 a, and an oil line that connectsthese. The oil return line 39 a is formed from an oil return valve 43 athat is a solenoid valve, a check valve 44 a, and an oil line thatconnects these. Then, an oil equalization circuit that serves toexchange the oil of the compression mechanisms of each heat source unit102 a–102 c is formed by the oil removal line 20 a and the oilequalization line 6 that serves to connect the compression mechanisms ofthe heat source units 102 a–102 c.

The refrigerant removal line 21 a is a refrigerant line that is arrangedsuch that refrigerant from between the four way switching valve 14 a andthe heat source side heat exchanger 15 a can be removed to the exteriorof the heat source unit, and includes a second open/close mechanism 45 athat is a solenoid valve, a check valve 46 a, and a refrigerant linethat connects these. In the present embodiment, the refrigerant removalline 21 a is connected to the oil removal line 20 a, and refrigerant isremoved to the exterior of the heat source unit via the oil equalizationline 6 that serves to connect the compression mechanisms of each heatsource unit 102 a–102 c. In other words, a refrigerant supply circuitthat serves to exchange refrigerant between each heat source unit 102a–102 c is formed by the refrigerant removal line 21 a, the oil removalline 20 a, and the oil equalization line 6.

The receiver pressurization circuit 22 a is a refrigerant line that isarranged such that refrigerant from between the discharge side of thecompression mechanism 13 a and the four way switching valve 14 a can besent directly to the intake port of the receiver 17 a, and includes athird open/closed mechanism 47 a that is a solenoid valve, a check valve48 a, a capillary 49 a, and a refrigerant line that connects these.

The receiver depressurization circuit 23 a is a refrigerant line that isarranged such that refrigerant from the upper portion of the receiver 17a can flow to the intake side of the compression mechanism 13 a, andincludes a fourth open/close valve 50 a that is a solenoid valve, and arefrigerant line that connects these.

In addition, various sensors are provided in the heat source unit 102 a.Specifically, a discharge temperature sensor 51 a that detects thedischarge refrigerant temperature of the compression mechanism 13 a anda discharge pressure sensor 52 a are provided on the discharge side ofthe compression mechanism 13 a. An intake temperature sensor 53 a thatdetects the intake refrigerant temperature of the compression mechanism13 a and an intake pressure sensor 54 a are provided on the intake sideof the compression mechanism 13 a. A heat exchange temperature sensor 55a that detects refrigerant temperature is provided on the liquid side ofthe heat source side heat exchanger 15 a. An outside air temperaturesensor 56 a that detects the temperature of the outside air is providednear the heat source side heat exchanger 15 a. Then, the apertures ofthe user side expansion valves 61 a, 61 b and the heat source sideexpansion valve 36 a (heat source side expansion valves 36 b, 36 c inthe case of the heat source units 102 b, 102 c) and the capacity of thecompression mechanism 13 a (the compression mechanisms 13 b, 13 c in thecase of the heat source units 102 b, 102 c) are controlled based uponthe detection signals of the various sensors provided in the user units3 a, 3 b.

Thus, with the air conditioner 1, although it will be necessary todirectly connect the heat source side branch liquid lines 11 a–11 c andthe heat source side branch gas lines 12 a–12 c to the refrigerantliquid junction line 4 and the refrigerant gas junction line 5, as wellas connect a communication line (which also serves as the oilequalization line 6 in the present embodiment) in order to exchangerefrigerant between the heat source units, compared to a conventionalconfiguration shown in FIG. 9 in which heat source side branch liquidlines 211 a–211 c and heat source side branch gas lines 212 a–212 c ofheat source units 202 a–202 c are connected to the refrigerant liquidjunction line 4 and the refrigerant gas junction line 5 via a line unit7, the merit that is obtained by the present invention is that the lineunit 7 can be eliminated.

(4) Operation of the Air Conditioner

Next, the operation of the air conditioner 1 will be described withreference to FIGS. 3–8. Here, FIG. 3 is an outline of the refrigerationcircuits of the heat source units 102 a–102 c when all of the heatsource units 102 a–102 c are performing cooling operations (the arrowsin the figure show the direction of the refrigerant and oil flows).FIGS. 4 and 5 are outlines of the refrigeration circuits of the heatsource units 102 a–102 c when the heat source units 102 a, 102 c areperforming cooling operations and the heat source unit 102 b is stopped(the arrows in the figure show the direction of the refrigerant and oilflows). FIG. 6 is an outline of the refrigeration circuits of the heatsource units 102 a–102 c when all of the heat source units 102 a–102 care performing heating operations (the arrows in the figure show thedirection of the refrigerant and oil flows). FIGS. 7 and 8 are outlinesof the refrigeration circuits of the heat source units 102 a–102 c whenthe heat source units 102 a, 102 c are performing heating operations andthe heat source unit 102 b is stopped (the arrows in the figure show thedirection of the refrigerant and oil flows).

1. Cooling Operations (When All Heat Source Units are Operating)

During cooling operations, the four way switching valves 14 a–14 c ofeach heat source unit 102 a–102 c are in the state illustrated by thesolid lines in FIG. 3, i.e., the state in which the discharge sides ofthe compression mechanisms 13 a–13 c are respectively connected to thegas sides of the heat source side heat exchangers 15 a–15 c, and theintake sides of the compression mechanisms 13 a–13 c are respectivelyconnected to the heat source side branch gas lines 12 a–12 c. Inaddition, the liquid side gate valves 18 a–18 c, the gas side gate valve19 a–19 c, the oil gate valves 42 a–42 c, and the first open/closemechanisms 37 a–37 c of each heat source unit are open. Furthermore, theoil return line 39 a is placed into a state in which it can be used, andthe refrigerant removal line 21 a, the receiver pressurization circuit22 a, and the receiver depressurization circuit 23 a are placed into astate in which they will not be used. In other words, the oil returnvalves 43 a–43 c are completely open, and the second open/closemechanisms 45 a–45 c, the third open/close mechanisms 47 a-47 c, and thefourth open/close mechanisms 50 a–50 c are closed. In addition, theapertures of the user side expansion valves 61 a, 61 b of the user units3 a, 3 b shown in FIG. 1 are adjusted so that the refrigerant pressureis reduced. The heat source side expansion valve 36 a–36 c are in theclosed state.

With the heat source unit refrigeration circuits in this state, thecompression mechanisms 13 a–13 c of each heat source units 102 a–102 cbegin operating. When this occurs, the high pressure refrigerant gasdischarged from each compression mechanism 13 a–13 c is condensed byeach heat source side heat exchanger 15 a–15 c and becomes refrigerantliquid, and this refrigerant liquid is merged into the refrigerantliquid junction line 4 via the bridge circuits 16 a–16 c (morespecifically the check valves 34 a-34 c), the receivers 17 a–17 c, thebridge circuits 16 a–16 c (more specifically the check valves 35 a–35c), and the heat source side branch liquid lines 11 a–11 c. After that,the pressure of the refrigerant liquid is reduced by the user sideexpansion valves 61 a, 61 b of the user unit 3 a, 3 b, and then therefrigerant liquid is evaporated by the user side heat exchangers 62 a,62 b and becomes a low pressure refrigerant gas. This refrigerant gas isbranched from the refrigerant gas junction line 5 to each heat sourceside branch gas line 12 a–12 c, returns to the compressor mechanisms 13a–13 c of each heat source unit 102 a–102 c, and then repeats thiscirculation operation.

Note that the oil discharged from the oil accumulation portion of eachcompression mechanism 13 a–13 c to, each oil discharge line 38 a–38 c isreturned to the intake side of the compression mechanisms 13 a–13 c byeach oil return line 39 a-39 c, and is drawn into each compressionmechanism 13 a–13 c together with the low pressure refrigerant.

2. Cooling Operations (When There is a Stopped Heat Source Unit Present)

When the cooling operational burden of the user units 3 a, 3 bdecreases, equipment control will be performed in response to this thatreduces the number of operational heat source units 102 a–102 c. Asituation in which only the heat source unit 102 b is stopped and theother two heat source units 102 a, 102 c are operating will be describedbelow with reference to FIGS. 4 and 5.

First, the compression mechanism 13 b of the heat source unit 102 b isstopped, and the first open/close mechanism 37 b and oil return valve 43b are closed. When this occurs, the refrigerant pressure from thedischarge side of the compression mechanism 13 b of the heat source unit102 b to the heat source side branch liquid line 11 b will be reduced.At this point, because the first open/close mechanism 37 b is closed,refrigerant liquid will not flow from the refrigerant liquid junctionline 4 into the heat source unit 102 b. In addition, the oil dischargedfrom the accumulation portion of the compressor 31 a of the compressionmechanism 13 b to the oil discharge line 38 b passes through the oilequalization line 6 and the oil return lines 39 a, 39 c, and is sent tothe intake side of the compression mechanisms 13 a, 13 c of the heatsource units 102 a, 102 c.

If the operation of the heat source units 102 a, 102 c continues in thisstate, refrigerant will be accumulated inside the stopped heat sourceunit 102 b, and the quantity of refrigerant that circulates between theuser units 3 a, 3 b and the operating heat source units 102 a, 102 cwill be reduced (a refrigerant shortage state). In the air conditioner1, whether or not a refrigerant shortage state exists can be determinedfrom the refrigerant temperature detected by the temperature sensors 63a, 64 a, 63 b, 64 b of the user units 3 a, 3 b and the apertures of theuser side expansion valves 61 a, 61 b. Then, as shown in FIG. 4, if itis determined that a refrigerant shortage state does exist, therefrigerant accumulated between the receiver 17 b and the check valve 32b arranged on the discharge side of the compressor 31 b of the heatsource unit 102 b passes through the refrigerant removal line 21 a andthe oil equalization line 6 and is supplied to the operating heat sourceunits 102 a, 102 c by opening the second open/close mechanism 45 b ofthe stopped heat source unit 102 b for only a predetermined time period.Here, the refrigerant liquid accumulated in the receiver 17 a of theheat source unit 102 b is evaporated by the heat source side heatexchanger 15 b, and then supplied to the intake side of the compressionmechanisms 13 a, 13 c. Then, this refrigerant gas passes through the oilreturn lines 39 a, 39 c of the heat source units 102 a, 102 c and issupplied to the intake side of the compression mechanisms 13 a, 13 c.Note that the second open/close mechanism 45 b will be closed after theexpiration of the predetermined time period, but if it is determinedafter closing the second open/close mechanism 45 b that the refrigerantshortage state has not been eliminated and that the refrigerant shortagestate still exists, the second open/close mechanism 45 b will be openedagain for only the predetermined time period. In this way, the quantityof refrigerant that circulates between the user units 3 a, 3 b and theuser heat source units 102 a, 102 c will be increased and therefrigerant shortage state will be eliminated.

Next, there will be times in which the refrigerant accumulated insidethe heat source unit 102 b will be supplied in excess to the operatingheat source units 102 a, 102 c and an excessive refrigerant state willbe created. As shown in FIG. 5, in this type of situation the secondopen/close mechanism 45 b of the stopped heat source unit 102 b will beclosed, and refrigerant will not be discharged from the interior of theheat source unit 102 b. After that, the refrigerant liquid will be madeto flow into the receiver 17 b from the refrigerant liquid junction line4 via the heat source side branch line 11 b by opening the firstopen/close mechanism 37 b, and the excessive refrigerant state will beeliminated. Even in this situation, the first open/close mechanism 37 bis opened for only a predetermined time period and then closed, and willbe re-opened for only the predetermined period of time if there is anexcessive refrigerant state.

Thus, even when some of the heat source units are stopped by means ofequipment control, an appropriate refrigerant circulation quantity canbe maintained by opening and closing the first and second open/closemechanisms 37 b, 45 b of the stopped heat source unit 102 b.

3. Heating Operations (When All Heat Source Units are Operating)

During heating operations, the four way switching valves 14 a–14 c ofeach heat source unit 102 a–102 c are in the state illustrated by thebroken lines in FIG. 6, i.e., the state in which the discharge sides ofthe compression mechanisms 13 a–13 c are respectively connected to theheat source side branch gas lines 12 a–12 c, and the intake sides of thecompression mechanisms 13 a–13 c are respectively connected to the gassides of the heat source side heat exchangers 15 a–15 c. In addition,the liquid side gate valves 18 a–18 c, the gas side gate valve 19 a–19c, the oil gate valves 42 a–42 c, and the first open/close mechanisms 37a–37 c of each heat source unit are open. Furthermore, the oil returnline 39 a is placed into a state in which it can be used, and therefrigerant removal line 21 a, the receiver pressurization circuit 22 a,and the receiver depressurization circuit 23 a are placed into a statein which they will not be used. In other words, the oil return valves 43a–43 c are completely open, and the second open/close mechanisms 45 a–45c, the third open/close mechanisms 47 a–47 c, and the fourth open/closemechanisms 50 a–50 c are closed. In addition, the apertures of the userside expansion valves 61 a, 61 b of the user unit 3 a, 3 b are adjustedin response to the heating burden of the user units 3 a, 3 b. Theapertures of the heat source side expansion valves 36 a-36 c arerespectively adjusted based upon the degree of refrigerant gassuperheating calculated from the refrigerant temperature and pressuredetected by the temperature sensor 53 a and the pressure sensor 54 a.

With the heat source unit refrigeration circuits in this state, thecompression mechanisms 13 a–13 c of each heat source units 102 a–102 cbegin operating. When this occurs, high pressure refrigerant gasdischarged from each compression mechanism 13 a–13 c is merged into therefrigerant gas junction line 5 via each heat source side branch gasline 12 a–12 c. After that, the refrigerant gas is condensed by the userside heat exchangers 62 a, 62 b of the user units 3 a, 3 b and becomesrefrigerant liquid, and the pressure of the refrigerant liquid isreduced by the user side expansion valves 61 a, 61 b. This refrigerantliquid is branched from the refrigerant liquid junction line 4 to eachheat source side branch liquid line 11 a–11 c, flows through the bridgecircuits 16 a–16 c (more specifically the first open/close mechanisms 37a–37 c and the check valves 33 a-33 c), the receivers 17 a–17 c, and thebridge circuits 16 a–16 c (more specifically the check valves 36 a–36c), is evaporated by the heat source side heat exchangers 15 a–15 c ofeach heat source side unit 102 a–102 c, then returns to the compressormechanisms 13 a–13 c, and then repeats this circulation operation.

Note that the oil discharged from the oil accumulation portion of eachcompression mechanism 13 a–13 c to each oil discharge line 38 a–38 cpasses through the oil return lines 39 a–39 c, is returned to the intakeside of the compression mechanisms 13 a–13 c, and is drawn into eachcompression mechanism 13 a–13 c together with the low pressurerefrigerant gas.

However, during heating operations, when the refrigerant sent from theuser side heat exchangers 62 a, 62 b of the user unit 3 a, 3 b to theheat source units 102 a–102 c via the refrigerant liquid junction line 4is branched from the refrigerant liquid junction line 4 to the heatsource side branch liquid lines 11 a–11 b of each heat source unit, anunequal flow will often be created because the refrigerant is in thegas-liquid phase. The air conditioner 1 of the present embodiment canoperate to eliminate unequal flow when this state is created. Theoperation of the heat source unit 102 b when the quantity of refrigerantsent from the refrigerant liquid junction line 4 to the heat source unit102 b is less than that sent to the other heat source units 102 a, 102 cwill be described below.

During heating operations, as noted above, the aperture of the heatsource side expansion valve 36 b is adjusted based upon the degree ofrefrigerant gas superheating calculated from the refrigerant temperatureand pressure detected by the temperature sensor 53 b and the pressuresensor 54 b. Because of this, the quantity of refrigerant suppliedinside the unit will be reduced, the degree of refrigerant gassuperheating will increase, and the aperture of the heat source sideexpansion valve 36 b will increase. However, even if the heat sourceside expansion valve 36 b is completely open, if the degree ofrefrigerant gas superheating increases, it will be determined that thequantity of refrigerant supplied inside the unit is insufficient, andthe fourth open/close mechanism 50 b will open for only a predeterminedtime period. When this occurs, the refrigerant inside the receiver 17 bwill be discharged to the intake side of the compression mechanism 13 bvia the receiver depressurization circuit 23 b, and the pressure insidethe receiver 17 b will be reduced. In this way, the quantity ofrefrigerant supplied from the refrigerant liquid junction line 4 to theheat source unit 102 b will increase. Then, if the time period that thefourth open/close mechanism 50 b equals the predetermined time period,the degree of refrigerant gas superheating has been reduced, or the heatsource side expansion valve 36 b has begun to close, the fourthopen/close mechanism 50 b will close. By operating the fourth open/closemechanism 50 b in this way, a refrigerant shortage in the heat sourceunit 102 b will be eliminated. Even with the other heat source units 102a, 102 c, the quantity of refrigerant sent from the refrigerant liquidjunction line 4 to each heat source unit will be maintained at anappropriate flow rate balance.

4. Heating Operations (When There is a Stopped Heat Source Unit Present)

When the heating operational burden of the user units 3 a, 3 bdecreases, equipment control will be performed in response to this thatreduces the number of heat source units 102 a–102 c that operate. Asituation in which only the heat source unit 102 b is stopped and theother two heat source units 102 a, 102 c are operating will be describedbelow with reference to FIGS. 7 and 8.

First, the compression mechanism 13 b of the heat source unit 102 isstopped, and the first open/close mechanism 37 b and oil return valve 43b are closed. At this point, because the first open/close mechanism 37 bis closed, refrigerant liquid will not flow from the refrigerant liquidjunction line 4 into the heat source unit 102 b. In addition, the oildischarged from the accumulation portion of the compressor 31 a of thecompression mechanism 13 b to the oil discharge line 38 b passes throughthe oil equalization line 6, and is sent to the intake side of thecompression mechanisms 13 a, 13 c of the heat source units 102 a, 102 c.

If the operation of the heat source units 102 a, 102 c continues in thisstate, refrigerant will accumulate inside the stopped heat source unit102 b, and the quantity of refrigerant that circulates in therefrigerant circuit will be reduced (a refrigerant shortage state). Inthe air conditioner 1, whether or not a refrigerant shortage stateexists can be determined from the refrigerant temperature detected bythe temperature sensors 63 a, 64 a, 63 b, 64 b of the user units 3 a, 3b and the apertures of the user side expansion valves 61 a, 61 b. Then,if it is determined that a refrigerant shortage state exists, therefrigerant accumulated in the stopped heat source unit 102 b will besupplied to the operating heat source units 102 a, 102 c.

Here, the speed with which refrigerant liquid accumulates in thereceiver 17 b may increase immediately after the heat source unitsconducting heating operations are stopped. If this occurs, like duringcooling operations, a sufficient refrigerant discharge speed may not beobtained by simply opening the second open/close mechanism 45 b. Becauseof this, as shown in FIG. 7, high pressure refrigerant gas from therefrigerant gas junction line 5 will be supplied to the receiver 17 bvia the heat source side branch gas line 12 b, the four way switchingvalve 14 b, and the receiver pressurization circuit 22 b by opening thethird open/close mechanism 47 b. When this occurs, the refrigerantliquid inside the receiver 17 b will be discharged to the exterior ofthe heat source unit via the heat source side branch liquid line 11 bbecause the receiver 17 b is pressurized and the pressure thereof ishigher than the pressure of the refrigerant liquid junction line 4.Thus, the refrigerant shortage state will be eliminated.

Next, the refrigerant accumulated inside the heat source unit 102 b maybe supplied in excess to the operating heat source units 102 a, 102 cand thus an excessive refrigerant state will be created. As shown inFIG. 8, in this type of situation the third open/close mechanism 47 b ofthe stopped heat source unit 102 b will be closed, and refrigerant willnot be discharged from the interior of the heat source unit 102 b. Afterthat, the refrigerant liquid will be made to flow into the receiver 17 bfrom the refrigerant liquid junction line 4 via the heat source sidebranch line 11 b by opening the first open/close mechanism 37 b, and theexcessive refrigerant state will be eliminated.

Thus, even when some of the heat source units are stopped by means ofequipment control, an appropriate refrigerant circulation quantity canbe maintained by opening and closing the first and third open/closemechanisms 37 b, 47 b of the stopped heat source unit 102 b.

(5) Other Embodiments

Although an embodiment of the present invention was described abovebased upon the figures, the specific configuration of the presentinvention is not limited to this embodiment, and can be modified withina range that does not depart from the essence of the invention.

1. Although the heat source units used in the air conditioner in theforegoing embodiment are the air cooling type which use outdoor air as aheat source, water cooling types or ice storage types of heat sourceunits may also be used.

2. Although only one compressor is included in a compression mechanismin the foregoing embodiment, the compression mechanism may include aplurality of compressors.

3. Although in the foregoing embodiment an oil equalization circuit isused to form the refrigerant supply circuit, the oil equalizationcircuit having an oil removal line and an oil equalization line providedin order to equalize the oil between the compression mechanisms of eachheat source unit, a configuration in which a separately providedcommunication line that communicates between the refrigerant removalline and the intake side of the compression mechanism of each heatsource unit may be used in situations in which the oil equalizationcircuit is a separate circuit structure.

INDUSTRIAL APPLICABILITY

If the present invention is used, the line unit in an air conditionerthat includes a plurality of heat source units can be eliminated, andincreases in the onsite line construction can be held to a minimum whilemaking it possible to adjust the amount of refrigerant in the airconditioner.

1. An air conditioner, comprising: a plurality of heat source unitshaving compressor mechanisms and heat source side heat exchangers; arefrigerant liquid junction line and a refrigerant gas junction linethat parallel connect each heat source unit; user units that includeuser side heat exchangers, the user units connected to the refrigerantliquid junction line and the refrigerant gas junction line; and arefrigerant supply circuit used in situations in which some of theplurality of heat source units stop operating in response to anoperational burden of the user units, the refrigerant supply circuitincluding refrigerant removal lines provided in each heat source unitthat serve to remove refrigerant that accumulates inside stopped heatsource units to the exterior thereof, and a communication line thatconnects the refrigerant removal lines and intake sides of thecompression mechanisms of operating heat source units.
 2. The airconditioner disclosed in claim 1, wherein the heat source side heatexchangers are connected to discharge sides of the compressionmechanisms; and each heat source unit further includes a heat sourceside branch liquid line (11 a–11 c) that is connected to a liquid sideof the heat source side heat exchanger and the refrigerant liquidjunction line, a receiver that is provided on the heat source sidebranch liquid line, and a heat source side branch gas line that isconnected to the intake side of the compression mechanism and arefrigerant gas junction line; wherein the refrigerant removal lines arearranged such that they remove refrigerant from between the dischargesides of the compression mechanisms and gas sides of the heat sourceside heat exchangers.
 3. The air conditioner disclosed in claim 2,wherein the heat source side branch liquid lines include refrigerantopen/close mechanisms that close so that refrigerant will not flow fromthe refrigerant liquid junction line to the inside of stopped heatsource units when accumulated refrigerant inside stopped heat sourceunits is to be removed to the exterior thereof via the refrigerantremoval lines.
 4. The air conditioner disclosed in claim 3, wherein therefrigerant open/close mechanisms can make refrigerant liquid that flowsin the refrigerant liquid junction line flow into stopped heat sourceunits when a quantity of refrigerant that flows between the user unitsand the operating heat source units reaches an excessive state.
 5. Theair conditioner disclosed in claim 1, wherein the heat source side heatexchangers are connected to discharge sides of the compressionmechanisms; and each heat source unit further includes a heat sourceside branch liquid line that is connected to a liquid side of the heatsource side heat exchanger and the refrigerant liquid junction line, aheat source side branch gas line that is connected to the discharge sideof the compression mechanism and a refrigerant gas junction line, and areceiver that is provided on the heat source side branch liquid line;wherein the refrigerant removal lines are arranged such that they removerefrigerant from between the intake sides of the compression mechanismsand gas sides of the heat source side heat exchangers.
 6. The airconditioner disclosed in claim 5, wherein the heat source side branchliquid lines include refrigerant open/close mechanisms that close sothat refrigerant will not flow from the refrigerant liquid junction lineto the inside of stopped heat source units when accumulated refrigerantinside stopped heat source units is to be removed to the exteriorthereof via the refrigerant removal lines.
 7. The air conditionerdisclosed in claim 6, wherein stopped heat source units further includereceiver pressurization circuits that make some of the refrigerant thatflows in the refrigerant gas junction line flow into the receivers viathe heat source side branch gas lines.
 8. The air conditioner disclosedin claim 6, wherein the refrigerant open/close mechanisms can makerefrigerant liquid that flows in the refrigerant liquid junction lineflow into stopped heat source units when a quantity of refrigerant thatflows between the user units and the operating heat source units reachesan excessive state.
 9. The air conditioner disclosed in claim 1, whereinthe communication line is an oil equalization line that equallydistributes oil between the compression mechanisms of each heat sourceunit.
 10. An air conditioner, comprising: a plurality of heat sourceunits that include compression mechanisms, heat source side heatexchangers connected to intake sides of the compression mechanisms, andreceivers that are connected to liquid sides of the heat source sideheat exchangers; a refrigerant liquid junction line and a refrigerantgas junction line that parallel connect each heat source unit; userunits that include user side heat exchangers, the user units connectedto the refrigerant liquid junction line and the refrigerant gas junctionline; and receiver depressurization circuits that make refrigerant flowout from the receivers of the heat source units that have a shortage ofrefrigerant to the intake sides of the compression mechanisms thereof.